Compounds having absorption with high intensity for specific light are used as optical elements of recording layers of optical recording media such as CD-Rs, DVD-Rs, DVD+Rs and BD-Rs, and of image display devices such as liquid crystal display devices (LCDs), plasma display panels (PDPs), electroluminescence displays (ELDs), cathode ray tube display devices (CRTs), fluorescent display tubes and field emission type displays.
In optical filters for image display devices such as liquid crystal display devices (LCDs), plasma display panels (PDPs), electroluminescent displays (ELDs), cathode ray tube display devices (CRTs), fluorescent display tubes and field emission type displays, various compounds that absorb light at wavelengths of 300 to 1,100 nm are used as light absorbing materials.
Furthermore, in recent years, light absorbing agents that selectively absorb wavelengths at specifically 380 to 500 nm are required so as to make the color purity and color separation of display elements sufficient to thereby improve image quality. For these light absorbing agents, it is required that the light absorption is particularly steep, i.e., that the half width of λmax is small, and that the functions are not lost by light, heat and the like.
Optical filters that are mainly used in liquid crystal display devices (LCDs) include color filters. Generally, three primary colors of RGB have been used for color filters, but it is difficult to impart hues of pure RGB by a single color material, and thus efforts for making hues to those of pure RGB have been made by using plural color materials. Therefore, color materials of yellow, orange, purple and the like other than RGB are also required.
For light absorbing agents used for color filters, organic and/or inorganic pigments have been used due to their high heat-resistance, but the pigments had a problem that they decrease the luminance of display devices since they are pigments, and this problem has been solved by increasing the luminance of light sources; however, in accordance with the trend of low power consumption, dyes having excellent solubility in solvents and resin compositions and high heat-resistance, and color filters using the dyes have been actively developed. Patent Literatures 1 to 3 each discloses a dye using a compound having a specific structure. Patent Literature 4 discloses an optical filter using a compound having a specific structure.
However, the dyes (compounds) described in these Literatures are not satisfiable from the viewpoints of solubility and heat-resistance.